added cast wallet public key (#10196)

* added cast wallet public key

* added test and made smol changes

* fmt

* Update crates/cast/src/cmd/wallet/mod.rs

---------

Co-authored-by: zerosnacks <95942363+zerosnacks@users.noreply.github.com>

Author: Rimeeeeee

crates/cast/src/cmd/wallet/mod.rs

@@ -3,7 +3,10 @@ use alloy_chains::Chain;
 use alloy_dyn_abi::TypedData;
 use alloy_primitives::{hex, Address, PrimitiveSignature as Signature, B256, U256};
 use alloy_provider::Provider;
-use alloy_signer::Signer;
+use alloy_signer::{
+    k256::{elliptic_curve::sec1::ToEncodedPoint, SecretKey},
+    Signer,
+};
 use alloy_signer_local::{
     coins_bip39::{English, Entropy, Mnemonic},
     MnemonicBuilder, PrivateKeySigner,
@@ -210,7 +213,16 @@ pub enum WalletSubcommands {
         #[command(flatten)]
         wallet: WalletOpts,
     },
+    /// Get the public key for the given private key.
+    #[command(visible_aliases = &["pubkey"])]
+    PublicKey {
+        /// If provided, the public key will be derived from the specified private key.
+        #[arg(long = "raw-private-key", value_name = "PRIVATE_KEY")]
+        private_key_override: Option<String>,
 
+        #[command(flatten)]
+        wallet: WalletOpts,
+    },
     /// Decrypt a keystore file to get the private key
     #[command(name = "decrypt-keystore", visible_alias = "dk")]
     DecryptKeystore {
@@ -398,6 +410,34 @@ impl WalletSubcommands {
                 let addr = wallet.address();
                 sh_println!("{}", addr.to_checksum(None))?;
             }
+            Self::PublicKey { wallet, private_key_override } => {
+                let wallet = private_key_override
+                    .map(|pk| WalletOpts {
+                        raw: RawWalletOpts { private_key: Some(pk), ..Default::default() },
+                        ..Default::default()
+                    })
+                    .unwrap_or(wallet)
+                    .signer()
+                    .await?;
+
+                let private_key_bytes = match wallet {
+                    WalletSigner::Local(wallet) => wallet.credential().to_bytes(),
+                    _ => eyre::bail!("Only local wallets are supported by this command"),
+                };
+
+                let secret_key = SecretKey::from_slice(&private_key_bytes)
+                    .map_err(|e| eyre::eyre!("Invalid private key: {}", e))?;
+
+                // Get the public key from the private key
+                let public_key = secret_key.public_key();
+
+                // Serialize it as uncompressed (65 bytes: 0x04 || X (32 bytes) || Y (32 bytes))
+                let pubkey_bytes = public_key.to_encoded_point(false);
+                // Strip the 1-byte prefix (0x04) to get 64 bytes for Ethereum use
+                let ethereum_pubkey = &pubkey_bytes.as_bytes()[1..];
+
+                sh_println!("0x{}", hex::encode(ethereum_pubkey))?;
+            }
             Self::Sign { message, data, from_file, no_hash, wallet } => {
                 let wallet = wallet.signer().await?;
                 let sig = if data {

crates/cast/tests/cli/main.rs

@@ -500,7 +500,20 @@ casttest!(wallet_private_key_from_mnemonic_option, |_prj, cmd| {
 
 "#]]);
 });
+// tests that `cast wallet public-key` correctly derives and outputs the public key
+casttest!(wallet_public_key_with_private_key, |_prj, cmd| {
+    cmd.args([
+        "wallet",
+        "public-key",
+        "--raw-private-key",
+        "0x59c6995e998f97a5a0044966f0945389dc9e86dae88c7a8412f4603b6b78690d"
+    ])
+    .assert_success()
+    .stdout_eq(str![[r#"
+0xba5734d8f7091719471e7f7ed6b9df170dc70cc661ca05e688601ad984f068b0d67351e5f06073092499336ab0839ef8a521afd334e53807205fa2f08eec74f4
 
+"#]]);
+});
 // tests that `cast wallet private-key` with derivation path outputs the private key
 casttest!(wallet_private_key_with_derivation_path, |_prj, cmd| {
     cmd.args([